One more thought I had:
I did some research, and found that Python’s os.system() is implemented using the C function system() from stdlib.h. That is, in turn, implemented (to the best of my understanding) by feeding the string to POSIX. Could it be that this problem arises out of a difference between the Bash shell I run in Terminal, and the POSIX shell? I really don’t understand the shells, and I wasn’t able to find good info on them.
Thanks again.